CN107356888A - A kind of time difference type fluxgate sensor and time difference read method - Google Patents
A kind of time difference type fluxgate sensor and time difference read method Download PDFInfo
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- CN107356888A CN107356888A CN201710593193.XA CN201710593193A CN107356888A CN 107356888 A CN107356888 A CN 107356888A CN 201710593193 A CN201710593193 A CN 201710593193A CN 107356888 A CN107356888 A CN 107356888A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/04—Measuring direction or magnitude of magnetic fields or magnetic flux using the flux-gate principle
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
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Abstract
The present invention relates to a kind of time difference type fluxgate sensor and time difference read method, it is that INVENTIONPeriodic digital voltage signal is produced by fpga logic signal processor, two-way is divided to give fpga logic signal processor by external magnetic field detection circuit I and zero cross detection circuit II respectively through D/A change-over circuits, magnetic field is tested using time difference measurements of the pumping signal amplitude between zero moment and induced signal peak value of pulse, the induced signal peak value of pulse moment is positioned using peak detection circuit, without considering influence of the induced signal changes in amplitude to the reading peak value of pulse moment.With existing individually from compared with induced signal reads two-way saturation time difference mode, induced signal amplitude, which diminishes, when solving the problems, such as to measure magnetic field needs to change threshold value or increases signal amplitude, simplify circuit structure, accelerate conversion speed, with less exciting current with regard to fluxgate normal operating conditions can be reached, the power consumption of fluxgate is effectively reduced, low-intensity magnetic field is measured suitable for dynamic in real time.
Description
Technical field：
The present invention relates to a kind of time type fluxgate sensor, is read especially by pumping signal and induced signal joint
Magnetic saturation time mode, and induced signal peak value of pulse is positioned by peak detection circuit, read pumping signal width
The time difference spent between zero moment and induced signal peak value of pulse carries out the fluxgate sensor of magnetic-field measurement and the time difference reads
Take method.
Background technology：
Fluxgate sensor is because of its small volume, the advantage such as in light weight, low in energy consumption, manufacturing cost is cheap, in geomagnetic observation, sky
Between the geophysics such as magnetic-field measurement, geological prospecting be widely used, achieve a series of achievements.In recent years, even-order harmonic
Type fluxgate in detection due to being disturbed by odd harmonic, circuit it is complicated and the problems such as need twin shaft Striking symmetry, development speed
Slowly.Time difference type fluxgate, using the magnetic hysteresis saturated phenomenon of soft magnetic materials magnetic core, pass through the time between induced signal pulse
The poor corresponding relation with tested magnetic field is detected, and has the advantages that detection is simple, strong antijamming capability.But sensing letter
Number superimposed noise interference so that uncertainty during Conventional temporal difference type fluxgate read access time difference be present, have a strong impact on fluxgate
The order of accuarcy of measurement.In order to make up above-mentioned deficiency, the research field of China's time difference type fluxgate sensor is expanded, it is proposed that
A kind of time difference type fluxgate sensor and time difference read method, when tested magnetic field be present, soft magnetic materials magnetic core reaches full
It can be changed with state for time, it is the magnetic saturation time to combine read access time difference using pumping signal and induced signal, to tested
Detected in magnetic field.
Disclosed in CN101545958A《Bidirectional magnetic saturated time difference fluxgate sensor》Disclosed in CN103941200A
《The sensibility variable formula time difference type fluxgate sensor and data processing method of trapezoidal wave excitation》It is not directed to utilize excitation letter
Number and induced signal joint read access time difference method, and it is studied, it is proposed that one kind is using pumping signal amplitude
Time difference between zero moment and induced signal pulse time reads the magnetic saturation time as detection limit, measures the one of tested magnetic field
Kind time difference type fluxgate sensor.The peak value of induced signal pulse is corresponding with the magnetic saturation state of magnetic core, due to utilizing peak
Lag time poor (Residence Times Difference, RTD) between value point measures, by adjusting threshold voltage
Catching the peak point of position pulse signal can be disturbed by noise factor, and core material contains magnetic noise in itself, precisely
It is relatively difficult to position peak point.The method for being slightly below induced signal peak value using shaping threshold value is detected to the time difference.Though
So it is avoided that and finds the error that peak point is brought, but induced signal noise caused by read access time difference on influences not subtract
It is few.In order to reduce influence of the noise to induced signal, it is proposed that a variety of filtering methods reduce noise, although can filter out
Harmonic components, but this method, mainly for the purpose of detection signal amplitude, a certain degree of distortion occurs in filtered signal, should
In the time difference is detected, have some limitations.
After excitation field is fixed, when extraneous measured target magnetic field increases to certain value, hysteresis curve changes, excitation
The larger time difference can be not only produced between the induced signal peak value of pulse that signal is exported by sensing element, can also reduce output
The amplitude of signal, when using the method read access time difference of induced signal shaping pulse, the setting of shaping thresholding is needed with tested
The change in magnetic field and change, or in the case of without considering tested magnetic field size, make induced signal using adaptive amplification
Export identical amplitude.Induced signal amplitude can change during due to measurement magnetic field, add the complexity of detection circuit
And the response time that the time difference reads.
Disclosed in CN103336252A《Lag time difference type fluxgate sensor signal detecting method》It is a kind of slow to propose
Stagnant time difference type fluxgate sensor signal detecting method, threshold is relied on for solving existing fluxgate sensor signal detecting method
Value, which is chosen, causes the technical problem that accuracy of detection is difficult to ensure that.Intended using the data point near induced signal positive negative pulse stuffing
Close, obtaining the position of pulse positive peak and negative pulse peak value on a timeline, to calculate lag time poor, so as to obtain being tested magnetic field
Intensity.
Disclosed in CN102944853A《A kind of method in the fluxgate sensor accurate measurement magnetic field using noise driving》
The sensing detection to magnetic field is realized with nonlinear effect of the noise as input source in fluxgate sensor, passes through induced electricity
Kinetic potential measure a period of time inner magnetic core material be in upper saturation state it is accumulative when ∑ TB+, the cumulative time in lower saturation state
∑TB-.By the cumulative time ∑ T in upper saturation stateB+With the cumulative time ∑ T in lower saturation stateB-Subtract each other, tired out
Count residence time difference Δ T=∑s TB+-∑TB-。
Disclosed in CN105866713A《Feedback of status formula autoexcitation fluxgate sensor》Propose a kind of anti-by state
The autoexcitation fluxgate sensor of hypersensitivity magnetic-field measurement is realized in feedback, is passed through using three identical magnetic flux gate cells
Unidirectional loop topology coupling, is adjusted to the amplitude and frequency of sensor self stimulation by feedback of status, solves magnetic flux
Door sensor normal work rely on dynamic excitation signal could normal work, and be activated signal generation apparatus steady in itself
The problem of qualitative and influence of noise.
Disclosed in CN106371039A《Time difference type fluxgate sensor common mode noise rejection device and noise suppressed side
Method》A kind of the time difference type fluxgate sensor common mode noise rejection device and noise suppressing method proposed, including detection circuit I
With reference circuit II, detect circuit I in pumping signal by fluxgate magnetic core output induced signal successively with pre-amplification circuit,
Second-order low-pass filter circuit, adder circuit, binary channels comparison circuit and digital signal acquiring circuit are connected.Reference circuit II
Fluxgate magnetic core is substituted using physical characteristic identical resistance, output signal is passed through with detecting I identical circuit of circuit,
Subtraction is done to two paths of signals collection result respectively, removes the common-mode noise in two paths of signals.
In the prior art there is not yet being positioned using peak detection circuit to induced signal peak value of pulse, peak value is calculated
Combine the poor method of read access time at the time of appearance and by pumping signal and induced signal to measure the time in tested magnetic field
Poor type fluxgate sensor.
The content of the invention：
The purpose of the present invention is that for above-mentioned the deficiencies in the prior art, there is provided a kind of time difference type fluxgate sensing
Device；
It is an object of the invention to provide a kind of time difference read method of time difference type fluxgate sensor.
Idea of the invention is that：One kind is provided and combines read access time difference mode to weak magnetic using pumping signal and induced signal
The sensor that field measures, is positioned by peak detection circuit to induced signal peak value of pulse point, obtains peak value appearance
At the time of.The magnetic of magnetic-field measurement is carried out using time difference of the pumping signal amplitude between zero moment and induced signal peak value of pulse
Open gate sensor.Solve fluxgate sensor needs to change thresholding in larger magnetic field process is measured because induced signal amplitude diminishes
The problem of value or increase signal amplitude.
The purpose of the present invention is achieved through the following technical solutions：
A kind of time difference type fluxgate sensor, digital voltage pumping signal is produced using fpga logic signal processor 5,
Two-way is divided to be given respectively by external magnetic field detection circuit I and zero cross detection circuit II at fpga logic signal through D/A change-over circuits 6
Device 5 is managed, two paths of signals passage time difference read method is obtained the time difference by fpga logic signal processor 5, and is transmitted to
STM32 time differences data storage 9 is stored；
External magnetic field detection circuit I includes：The excitation coil both ends that V/I change-over circuits 1 are connected to sensing element 2 produce excitation
Magnetic field so that magnetic core reaches two-way hypersaturated state.Sensing element 2 includes excitation coil, induction coil, magnetic core and skeleton.
In terms of magnetic core selection, magnetic core of the horizontal low magnetic material of magnetic noise as sensing element can be chosen, such as cobalt base amorphous material,
Or using soft magnetic materials made of other casting technologies, it is horizontal to reduce magnetic noise.When in the presence of the tested magnetic field parallel to magnetic core
When, the time that induced signal reaches positive negative sense saturation state will change, induction coil output and the preceding storing of sensing element 2
Big circuit 3 is connected to be amplified to induced signal, and peak detection circuit 4 is input to after amplification；Peak detection circuit 4 is by just
To peakvalue's checking 41 and the composition of negative peak detection 42, two parts output is connected with amplifying circuit 43；
Zero cross detection circuit II includes：Driving voltage signal is passed through into amplifying circuit 7 and high speed Zero-cross comparator circuit successively
8；
Magnetic core reaches the time of positive and negative saturation state in the presence of excitation field and does not have HxWhen compared to being changed.
Because pumping signal is relatively accurate, is combined using pumping signal with induced signal and read the change that magnetic core reaches negative saturation or positive saturation
Change the time.Pumping signal amplitude is t at the time of being zero0, when the magnetic field intensity being applied on magnetic core is equal to coercivity-HcWhen, sensing
It is t that voltage, which can produce the negative pulse moment,1, when the magnetic field intensity being applied on magnetic core is equal to coercivity HcWhen, induced voltage can produce
The positive pulse moment is t2.It is zero moment t using pumping signal amplitude0Make reference point, detection induced signal reaches negative by positive pulse
Pulse time t1Or t at the time of directly reaching positive pulse2, utilize t0With t1Or t2Time difference Δ TMST, measure tested magnetic field
Hx, reach the purpose for measuring low-intensity magnetic field.
A kind of time difference read method of time difference type fluxgate sensor, comprises the following steps：
A, driving voltage signal amplified circuit 7 and high speed Zero-cross comparator circuit 8 all the way, is obtained synchronous with pumping signal
Rectangular signal, rectangular signal is input to the CH1 passages of fpga logic signal processor 5；
B, driving voltage signal by V/I change-over circuits 1 all the way by forming excitation cycle electric current, successively by sensing element
2nd, pre-amplification circuit 3, peak detection circuit 4, the rectangular signal containing tested Magnetic Field is obtained, rectangular signal is input to
The CH2 passages of fpga logic signal processor 5；
C, pumping signal is combined with induced signal reads the transformation period that magnetic core reaches negative saturation or positive saturation, i.e., using sharp
Encourage signal amplitude and make reference point for zero moment, detection induced signal reaches negative pulse by positive pulse or directly reaches positive pulse
Time, then when fpga logic signal processor 5 counts to two paths of signals, the trailing edge of CH1 passages, which counts, to be started, until
CH2 passages rising edge or trailing edge, which count, to be terminated, and output is time not good enough number N；
D, time point number N is converted into the time differenceWherein fcFor the meter of fpga logic signal processor 5
Number frequency.
When time difference type fluxgate works, magnetic core is magnetized to two-way supersaturation under the excitation of periodicity alternating magnetic field
State.Magnetic field H is tested when existingxWhen, the time that magnetic core rests on positive and negative saturation state can be influenceed so that the residence time becomes
Change.Utilize pumping signal He(t) time that magnetic core reaches saturation is reacted with induced signal ε (t) time differences special occasion, so as to survey
The tested magnetic field H of amountxSize.
Periodic activation signals H is inputted on excitation coile(t), when magnetic core reaches positive and negative saturation state, induction coil
On obtain pulse voltage signal ε (t), when the magnetic field intensity being applied on magnetic core is equal to coercivity-HcWhen, induced voltage can produce
Negative pulse, it is now t1.Utilize pumping signal He(t) t at the time of amplitude is zero0With t1Time difference Δ TMSTTo measure tested magnetic
Field Hx。
Periodic activation signals H is inputted on excitation coile(t), when magnetic core reaches positive and negative saturation state, induction coil
On obtain pulse voltage signal ε (t), when the magnetic field intensity being applied on magnetic core is equal to coercivity HcWhen, induced voltage can produce
Positive pulse, it is now t2, utilize pumping signal He(t) amplitude is the t of zero moment0With t2Time difference Δ TMSTThe tested magnetic field H of measurementx。
Excitation signal waveforms can choose sine wave, triangular wave or trapezoidal wave.
When sinus wave patters are as excitation field, sensitivity raises with the increase in measured target magnetic field.With triangular wave
When mode is as excitation field, if the amplitude of pumping signal and frequency are certain, the sensitivity of time difference type fluxgate sensor
For steady state value.
When sensitivity is steady state value, pumping signal chooses triangular wave, in order to ensure this kind of method sensitivity and two-way saturation
Time difference read method is identical, the slope of triangular wave pumping signalMSTFor the 1/4 of two-way saturation pumping signal slope.
Beneficial effect：Using pumping signal amplitude be time difference between zero moment and induced signal peak value of pulse be detection
The time difference type fluxgate of method, because pumping signal is relatively accurate, induced signal noise is reduced in read access time difference
Influence, with two-way saturation time difference detection method sensitivity identical under the premise of, can increase output response stability, improve
The accuracy of detection of fluxgate sensor signal.The fluxgate sensor of the present invention is that inductive impulse is believed using peak detection circuit
Number positive peak value and negative peak go out current moment and positioned, without considering that induced signal changes in amplitude was read the peak value of pulse moment
The influence taken.With existing individually from compared with induced signal reads two-way saturation time difference mode, sensing can be effectively reduced
Signal noise both ensure that the high sensitivity of fluxgate in unstability caused by time shaft, improve the steady of output response again
It is qualitative.Using peak detection circuit, peak value can be accurately detected, fluxgate sensor is solved and is measuring larger magnetic field process
It is middle because induced signal amplitude diminish need change threshold value or increase signal amplitude the problem of.Measure time to peak and pulse width
Spend unrelated, it is not necessary to complicated subsequent conditioning circuit, simplify circuit structure, conversion speed is faster, power consumption is lower, accuracy of detection
It is higher.And less exciting current can just reach fluxgate normal operating conditions, be effectively reduced fluxgate sensor
Power consumption, suitable for fluxgate, dynamic measures to low-intensity magnetic field in real time.
Brief description of the drawings：
Fig. 1 is a kind of time difference type fluxgate sensor structured flowchart
Fig. 2 is peak detection circuit figure
Fig. 3 is positive peak detection circuit figure
Fig. 4 is negative peak detection circuit diagram
Fig. 5 is as tested magnetic field HxWhen=0, pumping signal combines the negative saturation time figure of reading with induced signal
Fig. 6 is as tested magnetic field HxWhen ≠ 0, pumping signal combines the negative saturation time figure of reading with induced signal
Fig. 7 is as tested magnetic field HxWhen=0, pumping signal is combined with induced signal reads positive saturation time figure
Fig. 8 is as tested magnetic field HxWhen ≠ 0, pumping signal is combined with induced signal reads positive saturation time figure
Embodiment：
It is described in further detail below in conjunction with the accompanying drawings with example：
A kind of time difference type fluxgate sensor, as shown in fig. 1, including fpga logic signal processor 5 produces fluxgate
Cycle sensor digital voltage pumping signal, cycle analog voltage signal is obtained by D/A change-over circuits 6, all the way through external magnetic field
The V/I change-over circuits 1 for detecting circuit I form excitation cycle electric current, exciting current and the excitation coil in fluxgate sensing element 2
It is connected, obtains excitation field and act on the magnetic core of sensing element 2, the magnetic field for receiving extraneous change is converted into by induction coil
Voltage signal, being output to progress induced signal amplification, peak detection circuit 4 in pre-amplification circuit 3 includes two parts：Positive peak
Circuit 41 and negative sense blob detection circuit 42 are detected, as shown in Figure 3 and Figure 4.By positive blob detection circuit 41 and negative sense blob detection electricity
Road 42 is connected through amplifier 43, as shown in Figure 2.
Pumping signal passes through the amplifying circuit 7 and high speed Zero-cross comparator circuit 8 of zero cross detection circuit II successively all the way in addition；
A kind of time difference read method of time difference type fluxgate sensor, comprises the following steps：
A, driving voltage signal amplified circuit 7 and high speed Zero-cross comparator circuit 8 all the way, is obtained synchronous with pumping signal
Rectangular signal, rectangular signal is input to the CH1 passages of fpga logic signal processor 5；
B, the another way of driving voltage signal forms excitation cycle electric current by V/I change-over circuits 1, successively by sensitive member
Part 2, pre-amplification circuit 3, peak detection circuit 4, the rectangular signal containing tested Magnetic Field is obtained, rectangular signal is inputted
To the CH2 passages of fpga logic signal processor 5；
C, pumping signal is combined with induced signal reads the transformation period that magnetic core reaches negative saturation or positive saturation, i.e., using sharp
Encourage signal amplitude and make reference point for zero moment, detection induced signal reaches negative pulse by positive pulse or directly reaches positive pulse
Time, then when fpga logic signal processor 5 counts to two paths of signals, the trailing edge of CH1 passages, which counts, to be started, until
CH2 passages rising edge or trailing edge, which count, to be terminated, and output is time not good enough number N；
D, time point number N is converted into the time differenceWherein fcFor the meter of fpga logic signal processor 5
Number frequency.
Because pumping signal is relatively accurate, is combined using pumping signal with induced signal and read magnetic core and reach negative saturation or just
The transformation period of saturation.Pumping signal amplitude is t at the time of being zero0, when the magnetic field intensity being applied on magnetic core be equal to coercivity-
HcWhen, it is t that induced voltage, which can produce the negative pulse moment,1, pumping signal combines the negative saturation time of reading with induced signal, such as Fig. 5 and
Shown in 6.When the magnetic field intensity being applied on magnetic core is equal to coercivity HcWhen, it is t that induced voltage, which can produce the positive pulse moment,2, excitation
Signal is combined with induced signal reads positive saturation time, as shown in FIG. 7 and 8.
When magnetic core axially has tested magnetic field HxWhen, the time that magnetic core is in two steady state points of double potential wells changes,
The time difference of the calculating excitation signal amplitude between zero moment and induced signal peak value of pulse moment obtains the magnetic saturation time.Using swash
It is zero moment t to encourage signal amplitude0Make reference point, detection induced signal reaches negative pulse moment t by positive pulse1Or directly reach
Positive pulse moment t2, utilize t0With t1Or t2Time difference Δ TMST, obtain tested magnetic field HxSize.
Embodiment 1
A kind of time difference type fluxgate sensor, including external magnetic field detection circuit I and two parts group of zero cross detection circuit II
Into the control of fpga logic signal processor 5 produces the cycle digital stimulus signal of triangular wave patterns, is obtained by D/A change-over circuits 6
To triangular wave driving voltage signal, signal detects the V/I change-over circuits 1 of circuit I through external magnetic field and forms excitation cycle electric current all the way,
Act on the excitation coil of fluxgate sensing element 2 and obtain periodic triangular wave excitation magnetic field, sensing element 2 includes excitation line
Circle, induction coil, magnetic core and skeleton, in terms of magnetic core selection, the horizontal low cobalt base amorphous material conduct of magnetic noise can be chosen
The magnetic core of sensing element 2, it is sensitive in the presence of periodic triangular wave excitation magnetic field when fluxgate sensor normal work
Magnetic core is by remagnetization to hypersaturated state in element 2.Induction coil will receive extraneous variation magnetic field and be converted into voltage signal,
It is output to the amplification that induced signal is carried out among pre-amplification circuit 3.Peak detection circuit 4 includes two parts：Positive blob detection
Circuit 41 and negative sense blob detection circuit 42, as shown in Figure 3 and Figure 4.By positive peak detection circuit and negative peak detection circuit
It is connected through amplifier, as shown in Figure 2.The induced signal of amplification passes through peak detection circuit 4, obtains positive and negative with induced signal
It is corresponding and carry the square wave of external magnetic field information to go out current moment to peak value, realizes that induced signal positively and negatively peak value while is examined
Survey, and testing result is sent to the CH2 passages of fpga logic signal processor 5；
Driving voltage signal is electric by the amplifying circuit 7 and high speed Zero-cross comparator of zero cross detection circuit II successively all the way in addition
Road 8 obtains the rectangular signal synchronous with pumping signal, is sent to the CH1 passages of fpga logic signal processor 5；
The square-wave signal that fpga logic signal processor 5 is obtained using two parts circuit counts, the trailing edge of CH1 passages
Counting starts, and terminates until CH2 passages rising edge counts, and output is time not good enough number N；Time point number N is changed
Into the time difference, send STM32 to and carry out data storage；
When the magnetic core of sensing element 2 axially has tested magnetic field HxWhen, because pumping signal is relatively accurate, using pumping signal
Combine with induced signal and read the tested magnetic field H of transformation period reaction that magnetic core reaches negative saturationxSize.Pumping signal amplitude is
It is t at the time of zero0, when the magnetic field intensity being applied on magnetic core is equal to coercivity-HcWhen, induced voltage can produce the negative pulse moment
For t1, as tested magnetic field Hx=0 and HxWhen ≠ 0, pumping signal combines the negative saturation time of reading with induced signal, such as the institutes of Fig. 5 and 6
Show.It is zero moment t using pumping signal amplitude0Make reference point, detection induced signal reaches negative pulse moment t by positive pulse1,
Utilize t0With t1Time difference Δ TMST。
When using triangular wave as excitation field, if excitation field peak value is Hm, slope α, cycle T, encourage magnetic
Field He(t) it is as follows up to formula：
When magnetic field intensity reaches the negative saturation state i.e. t of magnetic core1When, excitation field He(t), it is tested magnetic field HxAnd coercivity
HcBetween relation it is as follows：
Obtained after entering line translation to above formula：
When using pumping signal amplitude as zero moment t0With induced signal negative pulse moment t1Joint reads magnetic core and reaches negative full
During with the read method of transformation period, the time difference Δ T of fluxgate sensorMSTAnd sensitivity SMSTExpression formula：
Now,
Negative sense magnetic saturation transformation period Δ T is read when combining using pumping signal with induced signalMSTWhen, pass through formula meter
Calculation can obtain, parallel to the tested magnetic field H in the magnetic core direction of sensing element 2xSize.
Embodiment 2
A kind of time difference type fluxgate sensor, including external magnetic field detection circuit I and two parts group of zero cross detection circuit II
Into the control of fpga logic signal processor 5 produces the cycle digital stimulus signal of triangular wave patterns, is obtained by D/A change-over circuits 6
To triangular wave driving voltage signal, signal detects the V/I change-over circuits 1 of circuit I through external magnetic field and forms excitation cycle electric current all the way,
Act on the excitation coil of fluxgate sensing element 2 and obtain periodic triangular wave excitation magnetic field, sensing element 2 includes excitation line
Circle, induction coil, magnetic core and skeleton, in terms of magnetic core selection, the horizontal low cobalt base amorphous material conduct of magnetic noise can be chosen
The magnetic core of sensing element 2, it is sensitive in the presence of periodic triangular wave excitation magnetic field when fluxgate sensor normal work
Magnetic core is by remagnetization to hypersaturated state in element 2.Induction coil will receive extraneous variation magnetic field and be converted into voltage signal,
It is output to the amplification that induced signal is carried out among pre-amplification circuit 3.Peak detection circuit 4 includes two parts：Positive blob detection
Circuit 41 and negative sense blob detection circuit 42, as shown in Figure 3 and Figure 4.By positive peak detection circuit and negative peak detection circuit
It is connected through amplifier, as shown in Figure 2.The induced signal of amplification passes through peak detection circuit 4, obtains positive and negative with induced signal
It is corresponding and carry the square wave of external magnetic field information to go out current moment to peak value, realizes that induced signal positively and negatively peak value while is examined
Survey, and testing result is sent to the CH2 passages of fpga logic signal processor 5；
Driving voltage signal is electric by the amplifying circuit 7 and high speed Zero-cross comparator of zero cross detection circuit II successively all the way in addition
Road 8 obtains the rectangular signal synchronous with pumping signal, is sent to the CH1 passages of fpga logic signal processor 5；
The square-wave signal that fpga logic signal processor 5 is obtained using two parts circuit counts, the trailing edge of CH1 passages
Counting starts, and terminates until CH2 passages trailing edge counts, and output is time not good enough number N；Time point number N is changed
Into the time difference, send STM32 to and carry out data storage；
When the magnetic core of sensing element 2 axially has tested magnetic field HxWhen, because pumping signal is relatively accurate, using pumping signal
Combine with induced signal and read the tested magnetic field H of transformation period reaction that magnetic core reaches positive saturationxSize.Pumping signal amplitude is
It is t at the time of zero0, when the magnetic field intensity being applied on magnetic core is equal to coercivity HcWhen, induced voltage can produce the positive pulse moment and be
t2, as tested magnetic field Hx=0 and HxWhen ≠ 0, pumping signal is combined with induced signal reads positive saturation time, as shown in FIG. 7 and 8.
It is zero moment t using pumping signal amplitude0Make reference point, detection induced signal directly reaches positive pulse moment t2, utilize t0With t2
Time difference Δ TMST。
When using triangular wave as excitation field, if excitation field peak value is Hm, slope α, cycle T, encourage magnetic
Field He(t) it is as follows up to formula：
When magnetic field intensity reaches the positive saturation state i.e. t of magnetic core2When, excitation field He(t), it is tested magnetic field HxAnd coercivity
HcBetween relation it is as follows：
t2:Hx+αt2=Hc
Obtained after entering line translation to above formula：
t2=(Hc-Hx)/α
When using pumping signal amplitude as zero moment t0With induced signal positive pulse moment t2Joint reads magnetic core and reaches just full
During with the read method of transformation period, the time difference Δ T of fluxgate sensorMSTAnd sensitivity SMSTExpression formula：
Now,
Hx=Hc-α·ΔTMST
Positive magnetic saturation transformation period Δ T is read when combining using pumping signal with induced signalMSTWhen, pass through formula meter
Calculation can obtain, parallel to the tested magnetic field H in the magnetic core direction of sensing element 2xSize.
Claims (7)
1. a kind of time difference type fluxgate sensor, it is characterised in that digital voltage is produced by fpga logic signal processor (5)
Pumping signal, two-way is divided to be given respectively by external magnetic field detection circuit I and zero cross detection circuit II through D/A change-over circuits (6)
Fpga logic signal processor (5), when fpga logic signal processor (5) obtains two paths of signals passage time difference read method
Between it is poor, and be transmitted to STM32 time differences data storage (9) storage；
External magnetic field detection circuit I is through sensing element (2), pre-amplification circuit (3), peakvalue's checking electricity by V/I change-over circuits (1)
Road (4) connects and composes；
Zero cross detection circuit II is connected and composed by amplifying circuit (7) and Zero-cross comparator circuit (8).
2. according to a kind of time difference type fluxgate sensor described in claim 1, it is characterised in that in external magnetic field detection circuit I
Peak detection circuit (4) be that (42) two-part output end is detected respectively with putting by positive peakvalue's checking (41) and negative peak
Big circuit (43) connects and composes.
3. according to a kind of time difference read method of time difference type fluxgate sensor described in claim 1, it is characterised in that bag
Include following steps：
A, pumping signal amplified circuit (7), Zero-cross comparator circuit (8) all the way, obtains the rectangular signal synchronous with pumping signal,
Rectangular signal is input to the CH1 passages of fpga logic signal processor (5)；
B, pumping signal another way forms excitation cycle electric current through V/I change-over circuits I, successively by sensing element (2), preceding storing
Big circuit (3) and peak detection circuit (4), obtain the rectangular signal containing external magnetic field information, rectangular signal are input into FPGA
The CH2 passages of logic signal processor (5)；
C, pumping signal is combined with induced signal reads the transformation period that magnetic core reaches negative saturation or positive saturation, that is, utilizes excitation letter
Number amplitude is that zero moment makees reference point, detection induced signal by positive pulse reach negative pulse or directly arrival positive pulse when
Between, then when fpga logic signal processor (5) counts to two paths of signals, the trailing edge of CH1 passages, which counts, to be started, until
CH2 passages rising edge or trailing edge, which count, to be terminated, and output is time not good enough number N；
D, time point number N is converted into the time differenceWherein fcFor the counting frequency of fpga logic signal processor (5)
Rate.
4. according to a kind of time difference read method of time difference type fluxgate sensor described in claim 3, it is characterised in that when
When time difference type fluxgate works, magnetic core is magnetized to two-way hypersaturated state, works as presence under the excitation of periodicity alternating magnetic field
Tested magnetic field HxWhen, the time that magnetic core rests on positive and negative saturation state can be influenceed so that the residence time changes, and utilizes excitation
Signal He(t) time that magnetic core reaches saturation is reacted with induced signal ε (t) time differences special occasion, so as to measure tested magnetic field Hx
Size.
5. according to a kind of time difference read method of time difference type fluxgate sensor described in claim 3, it is characterised in that
Periodic activation signals H is inputted on excitation coile(t), when magnetic core reaches positive and negative saturation state, pulse is obtained on induction coil
Voltage signal ε (t), when the magnetic field intensity being applied on magnetic core is equal to coercivity-HcWhen, induced voltage can produce negative pulse, this
When be t1, utilize pumping signal He(t) amplitude is zero moment t0With t1Time difference Δ TMSTThe tested magnetic field H of measurementx。
6. according to a kind of time difference read method of time difference type fluxgate sensor described in claim 3, it is characterised in that
Periodic activation signals H is inputted on excitation coile(t), when magnetic core reaches positive and negative saturation state, pulse is obtained on induction coil
Voltage signal ε (t), when the magnetic field intensity being applied on magnetic core is equal to coercivity HcWhen, induced voltage can produce positive pulse, now
For t2, utilize pumping signal He(t) amplitude is zero moment t0With t2Time difference Δ TMSTThe tested magnetic field H of measurementx。
7. according to a kind of time difference read method of time difference type fluxgate sensor described in claim 3, it is characterised in that swash
Sine wave, triangular wave or trapezoidal wave can be chosen by encouraging signal waveform.
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